The science and technology of coherent optical data processing (CODP) has existed as a recognized discipline since the early 1950's when the following authors and others published in the initial concepts upon which the field is now based. such authors include:
1. D. Gabor, Mass. Inst. of Tech., Electronics Research Laboratory Tech. Rep. No. 238 (1952).
2. E. L. O'Neill, I.R.E. Trans. on Infor. Theory, IT-2, Pg. 56 (1956).
3. A. Blank Lapierre, Symposium on Microwave Optics, McGill Univ., Montreal, Canada, Pg. 46 (1953).
4. P. Elias, et al, J. Opt. Soc. Am. 42, Pg. 127 (1952).
5. P. M. Duffieux, L'Integrable de Fourier et ses Applications a L'Optique, Faculte des Sciences, Besancon, France (1946 ).
6. A. Marachal and P. Croce, compte rendu, 237, Pg. 607 (1953).
7. L. Cutrona, et al, IRE Trans. on Infor. Theory, IT-6, Pg. 386 (1960 ).
The above noted U.S. Pat. No. 3,744,879 to T. D. Beard describes a more recent implementation of a coherent optical data processor using a transmissive liquid crystal light valve as a spatial filter to control transmissivity of coherent light through the processor. Not only is the Beard liquid crystal light valve transmissive rather than reflective, but also it relies on the dynamic scattering mode which has not proven as satisfactory in operation as the hybrid field effect mode to be described herein.
The promise of CODP, from the start, has been to perform data processing in many parallel processing channels simultaneously and quickly. Thus it was regarded to be an alternative to the serially organized electronic digital computer, particularly suited to the processing of two-dimensional data bases such as photographic images or multi-channel, wide bandwidth electronic signals. Despite its obvious advantages, CODP has not been regarded as a general purpose data processing technology. Inherently, CODP is a linear, analog process. For these reasons, and because the physical components and subsystems that implement these processes are non-programmable, CODP is substantially less flexible than is the electronic digital computer. As a result, CODP is best implemented in the form of special purpose processing hardware.
There exists many problem areas than can make use of such a special purpose processing capability. Unfortunately, few have heretofore benefited from the potentials of CODP. One of the principle reasons is that CODP, as it has heretofore been practiced, cannot be performed in real time. Speed of data through-put is a basic requirement for a special purpose data processor. Yet CODP, because of its historic reliance on photographic film both for inputting data and for use as a spatial filter, has been an off-line process. This is also true of the Beard device which relies on a Transparency, 60, for inputting a signal image. Thus CODP has suffered the worst of both processing worlds - - limited flexibility and off-line operation.
The light valve device of the present invention can resolve this dilemma by providing a high performance, real time non-coherent to coherent light image converter. The device may be used to input images in real-time from non-coherently illuminated scenes to the spatially coherent illumination of the CODP. The device may, of course, also be used in other image processing and projecting systems known to the prior art and not specifically intended for data processing applications.